The present invention relates to a swing arm for magnetic disc. More particularly, the present invention relates to a swing arm for magnetic disc, which comprises a plurality of arm members, the arm members being connected together to be integral with each other.
FIG. 7 is a general oblique view illustrating an embodiment of the swing arm for magnetic disc. The swing arm for magnetic disc is conventional, and complete of the present invention. The swing arm for magnetic disc 11 has an arm portions 11, 12, 22, 32, and a cylindrical portion 42. The cylindrical portion 42 has a fitting hole 41 in which a bearing for supporting a spindle (not shown) is fitted. Thereby, the swing arm for magnetic disc 11 swings about the spindle. The swing arm for magnetic disc 11 has a plurality of arm portions 12, 22, 22, 32 extending forward form the cylindrical portion 42, and formed in spaced relation between its top position and its bottom position, and a movable coil-winding portion 46 arranged on the side opposite from the arms 12, 22, 22, 32 and extending from the side of the cylindrical portion 42. Conventionally, the fitting hole 41, cylindrical portion 42, the plurality of arms 12, 22, 22, 32, and the movable coil-winding portion 46 were integrally formed into a single structural member as the swing arm for magnetic disc 11.
In conventional production of the above swing arm for magnetic disc, firstly, a rough body having arm portions and a cylindrical portion integrally formed therewith and made of material such as aluminum, was fashioned except with the movable coil-winding portion by a combination of die casting and extrusion processes.
After the body with arm and cylindrical portions that were integrally formed, has been rough fashioned, the shape required for the body were machined and finished. Thus, the form of the body with the arm and cylindrical portions was taken on form used as the product.
With the practice described above, expensive machines and tools for cutting were required, and the resultant product cost was also expensive because of required long time for the works. Thus, the conventional swing arm for magnetic disc had inconvenient problems.
Considering the above problems in the conventional production, the present invention provides a swing arm for magnetic disc, which comprises a plurality of arm members made of metal material, the arm members being assembled with each other in integrally formed relation. The swing arm for magnetic disc can be produced without the cutting work requiring the use of the machines and tools for cutting.
In order to achieve the above objects, the swing arm for magnetic disc provided herein comprises a plurality of arm members connected together to be integral with each other, each of the arm members being made of a metal material, the arm members having a top surface, a bottom surface, an arm portion formed in one side thereof for fixing gimbals, and a cylindrical portion formed in opposite end side from the arm portion, the arm portions being arranged in spaced relation between the up and down positions, the cylindrical portion extending from the top surface of the arm member and protruding downwardly from the bottom surface of the arm member, the cylindrical portion each having a large diameter cylindrical portion and a small diameter cylindrical portion, the large and small diameter cylindrical portions of the arm members each having equal outside diameter to each other, the swing arm for magnetic disc having a top arm member, at least one or more intermediate arm members, and a lower arm member of the arm members, the cylindrical portion of the top arm member having an inside diameter which is of a predetermined distance, the cylindrical portion in the top arm member having the small diameter cylindrical portion which is of a predetermined sleeve length, the intermediate and lower arm member each having a large diameter hole portion, the large diameter hole portion having an inside diameter substantially equal to the outside diameter of the small diameter cylindrical portion of the top arm member, the large diameter cylindrical portion in the intermediate and lower arm members each having a sleeve length substantially equal to the sleeve length of the small diametrical portion of the top arm member, the cylindrical portions of the top, intermediate, and lower arm members each being stepped through the inside diameters of the large and small diameter cylindrical portions to provide a receiver portion thereon, the cylindrical portions of the top arm member having a fitting hole formed in the inside diameter thereof, the intermediate and lower arm members each having a fitting hole extending from the large diameter hole to the end of the small diameter cylindrical portion of the cylindrical portion thereof, the small diameter cylindrical portion of the cylindrical portion of the top arm member being fitted in the large diameter hole of the cylindrical portion in the intermediate arm member, the small diameter cylindrical potion being fitted in the large diameter hole of the cylindrical portion of another intermediate arm member or the lower arm member, the shoulder portion of the cylinder portion of the top, and intermediate arm members contacting with the top surface of another intermediate arm member or the lower arm member, respectively, the lowermost end surface of the cylindrical portions of the top, intermediate, or lower arm members contacting with the receiver portion of the cylindrical portion of another intermediate arm member or the lower arm member, the fitting holes of the cylindrical portions of the top, intermediate, and lower arm members being coupled and communicated with each other so as to be integral with each other.
By virtue of the construction in the above swing arm for magnetic disc, one of the intermediate arm members in the swing arm for magnetic disc can be provided with a holding portion for holding a movable coil portion. It is desired that the holding portion in the swing arm for magnetic disc are freely formed. Preferably, the cylindrical portions each having the fitting hole connected in the assembling relation with each other may be fixedly integrated through resin coating layer on the periphery thereof, the resin coating layer being applied into the desirable shape.